Intracarotid injection of granulocyte-macrophage colony-stimulating factor induces neuroprotection in a rat transient middle cerebral artery occlusion model

Intrauterine Growth Restriction Alters Postnatal Hippocampal Dentate Gyrus Neuron and Microglia Morphology and Cytokine/Chemokine Milieu in Mice

Infants born with intrauterine growth restriction (IUGR) have up to a five-fold higher risk of learning and memory impairment than those with normal growth. Using a mouse model of hypertensive diseases of pregnancy (HDP) to replicate uteroplacental insufficiency (UPI), we have previously shown that UPI causes premature embryonic hippocampal dentate gyrus (DG) neurogenesis in IUGR offspring. The DG is a brain region that receives the first cortical information for memory formation. In the current study, we examined the postnatal DG neuron morphology one month after delivery (P28) using recombinant adeno-associated viral labeling of neurons. We also examined DG microglia's morphology using immunofluorescent histochemistry and defined the hippocampal cytokine/chemokine milieu using Luminex xMAP technology. We found that IUGR preserved the principal dendrite lengths but decreased the dendritic branching and volume of DG neurons. IUGR augmented DG microglial number and cell size. Lastly, IUGR altered the hippocampal cytokine/chemokine profile in a sex-specific manner. We conclude that the prematurely-generated neuronal progenitors develop abnormal morphologies postnatally in a cell-autonomous manner. Microglia appear to modulate neuronal morphology by interacting with dendrites amidst a complex cytokine/chemokine environment that could ultimately lead to adult learning and memory deficits in our mouse model.

An open-label multiyear study of sargramostim-treated Parkinson's disease patients examining drug safety, tolerability, and immune biomarkers from limited case numbers

BACKGROUND

The clinical utility and safety of sargramostim has previously been reported in cancer, acute radiation syndrome, autoimmune disease, inflammatory conditions, and Alzheimer's disease. The safety, tolerability, and mechanisms of action in Parkinson's disease (PD) during extended use has not been evaluated.

METHODS

As a primary goal, safety and tolerability was assessed in five PD patients treated with sargramostim (Leukine®, granulocyte-macrophage colony-stimulating factor) for 33 months. Secondary goals included numbers of CD4+ T cells and monocytes and motor functions. Hematologic, metabolic, immune, and neurological evaluations were assessed during a 5-day on, 2-day off therapeutic regimen given at 3 μg/kg. After 2 years, drug use was discontinued for 3 months. This was then followed by an additional 6 months of treatment.

RESULTS

Sargramostim-associated adverse events included injection-site reactions, elevated total white cell counts, and bone pain. On drug, blood analyses and metabolic panels revealed no untoward side effects linked to long-term treatment. Unified Parkinson's Disease Rating Scale scores remained stable throughout the study while regulatory T cell number and function were increased. In the initial 6 months of treatment, transcriptomic and proteomic monocyte tests demonstrated autophagy and sirtuin signaling. This finding paralleled anti-inflammatory and antioxidant activities within both the adaptive and innate immune profile arms.

CONCLUSIONS

Taken together, the data affirmed long-term safety as well as immune and anti-inflammatory responses reflecting clinical stability in PD under the sargramostim treatment. Confirmation in larger patient populations is planned in a future phase II evaluation.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03790670, Date of Registration: 01/02/2019, URL: https://clinicaltrials.gov/ct2/show/NCT03790670?cond=leukine+parkinson%27s&draw=2&rank=2 .

Granulocyte-macrophage colony-stimulating factor-triggered innate immune tolerance against chronic stress-induced behavioral abnormalities in mice

Pre-stimulation of the innate immune is considered a potential strategy to prevent chronic stress-induced behavioral abnormalities in animals. In this study, we investigated whether granulocyte-macrophage colony-stimulating factor (GM-CSF), an immunostimulant used in the clinic to treat diseases of the hematopoietic system, can prevent chronic stress-induced behavioral abnormalities in mice. Our results showed that a single intraperitoneal injection of GM-CSF (100 μg/kg) one day before stress exposure prevented the depression- and anxiety-like behaviors induced by chronic social defeat stress (CSDS) in mice, including preventing the CSDS-induced increase in the immobility time in the tail suspension test and forced swimming test and decrease in the time spent in the interaction zone in the social interaction test, as well as preventing the CSDS-induced decrease in the time spent (i) in open arms in the elevated plus maze test, (ii) on the illuminated side in the light-dark test, and (iii) in the central region of the open field test. The single GM-CSF preinjection (100 μg/kg) also prevented the CSDS-induced increase in the expression levels of interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) mRNA in the hippocampus and medial prefrontal cortex of the mice. Further analysis showed that the preventive effect of GM-CSF on CSDS-induced depression- and anxiety-like behaviors and neuroinflammatory responses was abolished by pretreatment with minocycline (an innate immune inhibitor). These results indicate that a single low dose of GM-CSF before injection could be a potential way to prevent behavioral abnormalities induced by chronic stress in mice.

Microglial re-modeling contributes to recovery from ischemic injury of rat brain: A study using a cytokine mixture containing granulocyte-macrophage colony-stimulating factor and interleukin-3

Ischemic stroke is a leading cause of mortality and permanent disability. Chronic stroke lesions increase gradually due to the secondary neuroinflammation that occurs following acute ischemic neuronal degeneration. In this study, the ameliorating effect of a cytokine mixture consisting of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-3 was evaluated on ischemic brain injury using a rat stroke model prepared by transient middle cerebral artery occlusion (tMCAO). The mixture reduced infarct volume and ameliorated ischemia-induced motor and cognitive dysfunctions. Sorted microglia cells from the ischemic hemisphere of rats administered the mixture showed reduced mRNA expression of tumor necrosis factor (TNF)-α and IL-1β at 3 days post-reperfusion. On flow cytometric analysis, the expression of CD86, a marker of pro-inflammatory type microglia, was suppressed, and the expression of CD163, a marker of tissue-repairing type microglia, was increased by the cytokine treatment. Immunoblotting and immunohistochemistry data showed that the cytokines increased the expression of the anti-apoptotic protein Bcl-xL in neurons in the ischemic lesion. Thus, the present study demonstrated that cytokine treatment markedly suppressed neurodegeneration during the chronic phase in the rat stroke model. The neuroprotective effects may be mediated by phenotypic changes of microglia that presumably lead to increased expression of Bcl-xL in ischemic lesions, while enhancing neuronal survival.

The innate immune system stimulating cytokine GM-CSF improves learning/memory and interneuron and astrocyte brain pathology in Dp16 Down syndrome mice and improves learning/memory in wild-type mice

Down syndrome (DS) is characterized by chronic neuroinflammation, peripheral inflammation, astrogliosis, imbalanced excitatory/inhibitory neuronal function, and cognitive deficits in both humans and mouse models. Suppression of inflammation has been proposed as a therapeutic approach to treating DS co-morbidities, including intellectual disability (DS/ID). Conversely, we discovered previously that treatment with the innate immune system stimulating cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF), which has both pro- and anti-inflammatory activities, improved cognition and reduced brain pathology in a mouse model of Alzheimer's disease (AD), another inflammatory disorder, and improved cognition and reduced biomarkers of brain pathology in a phase II trial of humans with mild-to-moderate AD. To investigate the effects of GM-CSF treatment on DS/ID in the absence of AD, we assessed behavior and brain pathology in 12-14 month-old DS mice (Dp[16]1Yey) and their wild-type (WT) littermates, neither of which develop amyloid, and found that subcutaneous GM-CSF treatment (5 μg/day, five days/week, for five weeks) improved performance in the radial arm water maze in both Dp16 and WT mice compared to placebo. Dp16 mice also showed abnormal astrocyte morphology, increased percent area of GFAP staining in the hippocampus, clustering of astrocytes in the hippocampus, and reduced numbers of calretinin-positive interneurons in the entorhinal cortex and subiculum, and all of these brain pathologies were improved by GM-CSF treatment. These findings suggest that stimulating and/or modulating inflammation and the innate immune system with GM-CSF treatment may enhance cognition in both people with DS/ID and in the typical aging population.

Safety and efficacy of sargramostim (GM-CSF) in the treatment of Alzheimer's disease

INTRODUCTION

Inflammatory markers have long been observed in the brain, cerebrospinal fluid (CSF), and plasma of Alzheimer's disease (AD) patients, suggesting that inflammation contributes to AD and might be a therapeutic target. However, non-steroidal anti-inflammatory drug trials in AD and mild cognitive impairment (MCI) failed to show benefit. Our previous work seeking to understand why people with the inflammatory disease rheumatoid arthritis are protected from AD found that short-term treatment of transgenic AD mice with the pro-inflammatory cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) led to an increase in activated microglia, a 50% reduction in amyloid load, an increase in synaptic area, and improvement in spatial memory to normal. These results called into question the consensus view that inflammation is solely detrimental in AD. Here, we tested our hypothesis that modulation of the innate immune system might similarly be used to treat AD in humans by investigating the ability of GM-CSF/sargramostim to safely ameliorate AD symptoms/pathology.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted in mild-to-moderate AD participants (NCT01409915). Treatments (20 participants/group) occurred 5 days/week for 3 weeks plus two follow-up (FU) visits (FU1 at 45 days and FU2 at 90 days) with neurological, neuropsychological, blood biomarker, and imaging assessments.

RESULTS

Sargramostim treatment expectedly changed innate immune system markers, with no drug-related serious adverse events or amyloid-related imaging abnormalities. At end of treatment (EOT), the Mini-Mental State Examination score of the sargramostim group increased compared to baseline (P = .0074) and compared to placebo (P = .0370); the treatment effect persisted at FU1 (P = .0272). Plasma markers of amyloid beta (Aβ40 [decreased in AD]) increased 10% (P = .0105); plasma markers of neurodegeneration (total tau and UCH-L1) decreased 24% (P = .0174) and 42% (P = .0019), respectively, after sargramostim treatment compared to placebo.

DISCUSSION

The innate immune system is a viable target for therapeutic intervention in AD. An extended treatment trial testing the long-term safety and efficacy of GM-CSF/sargramostim in AD is warranted.

Granulocyte-macrophage colony-stimulating factor neuroprotective activities in Alzheimer's disease mice

We investigated the effects of granulocyte-macrophage colony stimulating factor (GM-CSF) on behavioral and pathological outcomes in Alzheimer's disease (AD) and non-transgenic mice. GM-CSF treatment in AD mice reduced brain amyloidosis, increased plasma Aβ, and rescued cognitive impairment with increased hippocampal expression of calbindin and synaptophysin and increased levels of doublecortin-positive cells in the dentate gyrus. These data extend GM-CSF pleiotropic neuroprotection mechanisms in AD and include regulatory T cell-mediated immunomodulation of microglial function, Aβ clearance, maintenance of synaptic integrity, and induction of neurogenesis. Together these data support further development of GM-CSF as a neuroprotective agent for AD.

Blood-brain barrier breakdown and neovascularization processes after stroke and traumatic brain injury

PURPOSE OF REVIEW

Angiogenesis or vascular reorganization plays a role in recovery after stroke and traumatic brain injury (TBI). In this review, we have focused on two major events that occur during stroke and TBI from a vascular perspective - what is the process and time course of blood-brain barrier (BBB) breakdown? and how does the surrounding vasculature recover and facilitate repair?

RECENT FINDINGS

Despite differences in the primary injury, the BBB changes overlap between stroke and TBI. Disruption of BBB involves a series of events: formation of caveolae, trans and paracellular disruption, tight junction breakdown and vascular disruption. Confounding factors that need careful assessment and standardization are the severity, duration and extent of the stroke and TBI that influences BBB disruption. Vascular repair proceeds through long-term neovascularization processes: angiogenesis, arteriogenesis and vasculogenesis. Enhancing each of these processes may impart beneficial effects in endogenous recovery.

SUMMARY

Our understanding of BBB breakdown acutely after the cerebrovascular injury has come a long way; however, we lack a clear understanding of the course of BBB disruption and BBB recovery and the evolution of individual cellular events associated with BBB change. Neovascularization responses have been widely studied in stroke for their role in functional recovery but the role of vascular reorganization after TBI in recovery is much less defined.

Paraquat and psychological stressor interactions as pertains to Parkinsonian co-morbidity

A number of epidemiological and experimental studies have implicated the non-selective herbicide, paraquat, in the development of sporadic Parkinson's disease (PD). While preclinical research has focused mainly on elucidating the nigrostriatal effects of paraquat, relatively little data are available concerning non-motor brain systems and inflammatory immune processes (which have been implicated in PD). Hence, in the present study, we sought to take a multi-system approach to characterize the influence of paraquat upon extra-nigrostriatal brain regions, as well ascertain whether the impact of the pesticide might be enhanced in the context of chronic intermittent stressor exposure. Our findings support the contention that paraquat itself acted as a systemic stressor, with the pesticide increasing plasma corticosterone, as well as altering neurochemical activity in the locus coeruleus, paraventricular nucleus of the hypothalamus, nucleus accumbens, dorsal striatum, and central amygdala. However, with the important exception striatal dopamine turnover, the stressor treatment did not further augment these effects. Additionally, paraquat altered inter-cytokine correlations and, to a lesser extent, circulating cytokine levels, and concomitant stress exposure modulated some of these effects. Finally, paraquat provoked significant (albeit modest) reductions of sucrose preference and weight gain, hinting at possible anhendonic-like or sickness responses. These data suggest that, in addition to being a well known oxidative stress generator, paraquat can act as a systemic stressor affecting hormonal and neurochemical activity, but largely not interacting with a concomitant stressor regimen.

Hematopoietic cytokines as therapeutic players in early stages Parkinson's disease

Parkinson’s disease (PD) is a devastating age related neurodegenerative disease that is believed to have a lengthy prodromal state. It is critical to find methods to harness compensatory recovery processes in order to slow or prevent the eventual progression of clinical symptoms. The current perspective paper argues that immune system signaling molecules represent such a promising therapeutic approach. Two cytokines of interest are granulocyte macrophage-colony stimulating factor (GM-CSF) and erythropoietin (EPO). These hematopoietic cytokines have been protective in models of stroke, neuronal injury, and more recently PD. It is our belief that these trophic cytokines can be used not only for cell protection but also regeneration. However, success is likely dependent on early intervention. This paper will outline our perspective on the development of novel trophic recovery treatments for PD. In particular, we present new data from our lab suggesting that EPO and GM-CSF can foster neural re-innervation in a “mild” or partial lesion PD model that could be envisioned as reflecting the early stages of the disease.

Granulocyte-macrophage colony stimulating factor exerts protective and immunomodulatory effects in cortical trauma

Neurodegeneration after traumatic brain injury is facilitated by innate and adaptive immunity and can be harnessed to affect brain repair. In mice subjected to controlled cortical impact (CCI), we show that treatment with granulocyte macrophage colony stimulating factor (GM-CSF) affects regulatory T cell numbers in the cervical lymph nodes coincident with decreased lesion volumes and increased cortical tissue sparing. This paralleled increases in neurofilament and diminished reactive microglial staining. Transcriptomic analysis showed that GM-CSF induces robust immune neuroprotective responses seven days following CCI. Together, these results support the therapeutic potential of GM-CSF for TBI.

Erythropoietin increases neuronal NDPKA expression, and NDPKA up-regulation as well as exogenous application protects cortical neurons from in vitro ischemia-related insults

Using proteomics, we identified nucleoside diphosphate kinase A (NDPKA; also known as NME/NM23 nucleoside diphosphate kinase 1: NME1) to be up-regulated in primary cortical neuronal cultures by erythropoietin (EPO) preconditioning. To investigate a neuroprotective role of NDPKA in neurons, we used a RNAi construct to knock-down and an adenoviral vector to overexpress the protein in cortical neuronal cultures prior to exposure to three ischemia-related injury models; excitotoxicity (L-glutamic acid), oxidative stress (hydrogen peroxide), and in vitro ischemia (oxygen-glucose deprivation). NDPKA down-regulation had no effect on neuronal viability following injury. By contrast, NDPKA up-regulation increased neuronal survival in all three-injury models. Similarly, treatment with NDPKA recombinant protein increased neuronal survival, but only against in vitro ischemia and excitotoxicity. These findings indicate that the NDPKA protein may confer a neuroprotective advantage following injury. Furthermore, as exogenous NDPKA protein was neuroprotective, it suggests that a cell surface receptor may be activated by NDPKA leading to a protective cell-signaling response. Taken together both NDPKAs intracellular and extracellular neuroprotective actions suggest that the protein is a legitimate therapeutic target for the design of drugs to limit neuronal death following stroke and other forms of brain injury.

Vascular remodeling after ischemic stroke: mechanisms and therapeutic potentials

The brain vasculature has been increasingly recognized as a key player that directs brain development, regulates homeostasis, and contributes to pathological processes. Following ischemic stroke, the reduction of blood flow elicits a cascade of changes and leads to vascular remodeling. However, the temporal profile of vascular changes after stroke is not well understood. Growing evidence suggests that the early phase of cerebral blood volume (CBV) increase is likely due to the improvement in collateral flow, also known as arteriogenesis, whereas the late phase of CBV increase is attributed to the surge of angiogenesis. Arteriogenesis is triggered by shear fluid stress followed by activation of endothelium and inflammatory processes, while angiogenesis induces a number of pro-angiogenic factors and circulating endothelial progenitor cells (EPCs). The status of collaterals in acute stroke has been shown to have several prognostic implications, while the causal relationship between angiogenesis and improved functional recovery has yet to be established in patients. A number of interventions aimed at enhancing cerebral blood flow including increasing collateral recruitment are under clinical investigation. Transplantation of EPCs to improve angiogenesis is also underway. Knowledge in the underlying physiological mechanisms for improved arteriogenesis and angiogenesis shall lead to more effective therapies for ischemic stroke.

Histological quantification of brain tissue inflammatory cell infiltration after focal cerebral infarction: a systematic review

Ischemic stroke is a leading cause of death and disability, and current treatments to limit tissue injury and improve recovery are limited. Cerebral infarction is accompanied by intense brain tissue inflammation involving many inflammatory cell types that may cause both negative and positive effects on outcomes. Many potential neuroprotective and neurorestorative treatments may affect, and be affected by, this inflammatory cell infiltration, so that accurate quantification of this tissue response is needed. We performed a systematic review of histological methods to quantify brain tissue inflammatory cell infiltration after cerebral infarction. We found reports of multiple techniques to quantify different inflammatory cell types. We found no direct comparison studies and conclude that more research is needed to optimize the assessment of this important stroke outcome.

Granulocyte macrophage colony-stimulating factor shows anti-apoptotic activity via the PI3K-NF-κB-HIF-1α-survivin pathway in mouse neural progenitor cells

Granulocyte macrophage-colony stimulating factor (GM-CSF) is a hematopoietic cytokine that plays a crucial role in regulating the proliferation, differentiation, and survival of hematopoietic cells. Recent studies have shown that GM-CSF also has anti-apoptotic effects and regulates the expression of anti-apoptotic genes including Bcl-2 family proteins in neuronal cells in vitro and in vivo. However, the mechanism underlying the anti-apoptotic function of GM-CSF is not well understood. In the present work, we examined the role of phosphoinositide 3-kinase (PI3K)-AKT signal pathway in the anti-apoptotic activity of GM-CSF in mouse neural progenitor cells (NPCs). In terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, the anti-apoptotic effect of GM-CSF (apoptotic population of approximately 8.17 %) on staurosporine-induced apoptosis of NPCs (31.09 %) was significantly blocked by LY294002, an inhibitor of PI3K signal (24.04 %). We found that the PI3K-AKT signal pathway induced by GM-CSF treatment activated nuclear factor κB (NF-κB) and increased the expression of hypoxia-inducible factor 1α (HIF-1α) in normoxic conditions. Analyses using specific small interfering RNAs (siRNAs) showed that NF-κB was an upstream molecule of HIF-1α and activated its expression at the mRNA level. Further analyses using the siRNAs and chromatin immunoprecipitation (ChIP) showed that HIF-1α was responsible for the induced expression of survivin, a member of the inhibitor of apoptosis proteins (IAPs). Each of the specific siRNAs for NF-κB, HIF-1α, and survivin inhibited significantly the anti-apoptotic activity of GM-CSF on the staurosporine-induced apoptosis in NPCs in TUNEL assays. The results of this study showed the downstream signals and mechanism of PI3K/AKT-mediated anti-apoptotic activity of GM-CSF in NPCs, particularly revealing the role of the NF-κB-HIF-1α-survivin cascade.

Colony stimulating factors (including erythropoietin, granulocyte colony stimulating factor and analogues) for stroke

BACKGROUND

Colony stimulating factors (CSFs), also called haematopoietic growth factors, regulate bone marrow production of circulating red and white cells, and platelets. Some CSFs also mobilise the release of bone marrow stem cells into the circulation. CSFs have been shown to be neuroprotective in experimental stroke.

OBJECTIVES

To assess (1) the safety and efficacy of CSFs in people with acute or subacute ischaemic or haemorrhagic stroke, and (2) the effect of CSFs on circulating stem and blood cell counts.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched September 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 4), MEDLINE (1985 to September 2012), EMBASE (1985 to September 2012) and Science Citation Index (1985 to September 2012). In an attempt to identify further published, unpublished and ongoing trials we contacted manufacturers and principal investigators of trials (last contacted April 2012). We also searched reference lists of relevant articles and reviews.

SELECTION CRITERIA

We included randomised controlled trials recruiting people with acute or subacute ischaemic or haemorrhagic stroke. CSFs included stem cell factor (SCF), erythropoietin (EPO), granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage colony stimulating factor (GM-CSF), macrophage-colony stimulating factor (M-CSF, CSF-1), thrombopoietin (TPO), or analogues of these. The primary outcome was functional outcome at the end of the trial. Secondary outcomes included safety at the end of treatment, death at the end of follow-up, infarct volume and haematology measures.

DATA COLLECTION AND ANALYSIS

Two review authors (TE and NS) independently extracted data and assessed trial quality. We contacted study authors for additional information.

MAIN RESULTS

We included a total of 11 studies involving 1275 participants. In three trials (n = 782), EPO therapy was associated with a significant increase in death by the end of the trial (odds ratio (OR) 1.98, 95% confidence interval (CI) 1.19 to 3.3, P = 0.009) and a non-significant increase in serious adverse events. EPO significantly increased the red cell count with no effect on platelet or white cell count, or infarct volume. Two small trials of carbamylated EPO have been completed but have yet to be reported. We included eight small trials (n = 548) of G-CSF. G-CSF was associated with a non-significant reduction in early impairment (mean difference (MD) -0.4, 95% CI -1.82 to 1.01, P = 0.58) but had no effect on functional outcome at the end of the trial. G-CSF significantly elevated the white cell count and the CD34+ cell count, but had no effect on infarct volume. Further trials of G-CSF are ongoing.

AUTHORS' CONCLUSIONS

There are significant safety concerns regarding EPO therapy for stroke. It is too early to know whether other CSFs improve functional outcome.

MRI assessment of the intra-carotid route for macrophage delivery after transient cerebral ischemia

The broad aim underlying the present research was to investigate the distribution and homing of bone marrow-derived macrophages in a rodent model of transient middle cerebral artery occlusion using MRI and ultrasmall superparamagnetic iron oxide (USPIO) to magnetically label bone marrow-derived macrophages. The specific aim was to assess the intra-carotid infusion route for bone marrow-derived macrophage delivery at reperfusion. Fifteen Sprague-Dawley rats sustained 1 h of middle cerebral artery occlusion. USPIO-labeled bone marrow-derived macrophages were slowly injected for 5 min immediately after reperfusion in ischemic animals (n=7), 1 h after the end of surgery in sham animals (n=5) and very shortly after anesthesia in healthy animals (n=3). Multiparametric MRI was performed at day 0, just after cell administration, and repeated at day 1. Immunohistological analysis included Prussian blue for iron detection and rat endothelial cell antigen-1 for endothelium visualization. Intra-carotid cell delivery brought a large number of cells to the ipsilateral hemisphere of the brain, as seen on both MRI and immunohistology. However, it was associated with high mortality (50%). The study of sham animals demonstrated that intra-carotid cell delivery could induce ischemic lesions and may thus favor additional brain damage. The present study highlights severe drawbacks to the intra-carotid delivery of macrophages at the time of reperfusion in this rodent model of transient cerebral ischemia. Multiparametric MRI appears to be a method of choice to monitor longitudinally the effects of cell infusion, allowing the assessment of both cell fate with the help of magnetic labeling and of potential tissue damage.

The hematopoietic cytokine granulocyte-macrophage colony stimulating factor is important for cognitive functions

We recently reported expression of hematopoietic growth factor GM-CSF and its receptor (GM-CSFR) in CNS neurons. Here we evaluated this system in learning and memory formation using GM-CSF deficient mice. In complementation, GM-CSF signalling was manipulated specifically in adult murine hippocampus by adeno-associated virus (AAV)-mediated GM-CSFR alpha overexpression or knock-down. GM-CSF ablation caused various hippocampus and amygdala-dependent deficits in spatial and fear memory while rendering intact basic parameters like motor function, inherent anxiety, and pain threshold levels. Corroborating these data, spatial memory of AAV-injected mice was positively correlated with GM-CSFRα expression levels. Hippocampal neurons of knock-out mice showed markedly pruned dendritic trees, reduced spine densities, and lower percentages of mature spines. Despite such morphological alterations, long-term potentiation (LTP) was unimpaired in the knock-out hippocampus. Collectively, these results suggest that GM-CSF signalling plays a major role in structural plasticity relevant to learning and memory.

Toll-like receptor 4 contributes to poor outcome after intracerebral hemorrhage

OBJECTIVE

Intracerebral hemorrhage (ICH) is a devastating stroke subtype in which perihematomal inflammation contributes to neuronal injury and functional disability. Histologically, the region becomes infiltrated with neutrophils and activated microglia followed by neuronal loss, but little is known about the immune signals that coordinate these events. This study aimed to determine the role of Toll-like receptor 4 (TLR4) in the innate immune response after ICH and its impact on neurobehavioral outcome.

METHODS

Transgenic mice incapable of TLR4 signaling and wild-type controls were subjected to striatal blood injection to model ICH. The perihematomal inflammatory response was then quantified by immunohistochemistry, whole brain flow cytometry, and polymerase chain reaction. The critical location of TLR4 signaling was determined by blood transfer experiments between genotypes. Functional outcomes were quantified in all cohorts using the cylinder and open field tests.

RESULTS

TLR4-deficient mice had markedly decreased perihematomal inflammation, associated with reduced recruitment of neutrophils and monocytes, fewer microglia, and improved functional outcome by day 3 after ICH. Moreover, blood transfer experiments revealed that TLR4 on leukocytes or platelets within the hemorrhage contributes to perihematomal leukocyte infiltration and the neurological deficit.

INTERPRETATION

Together, these data identify a critical role for TLR4 signaling in perihematomal inflammation and injury and indicate this pathway may be a target for therapeutic intervention.

Granulocyte macrophage-colony stimulating factor shows anti-apoptotic activity in neural progenitor cells via JAK/STAT5-Bcl-2 pathway

Recently, many studies have shown that granulocyte macrophage-colony stimulating factor (GM-CSF) has anti-apoptotic activity and regulates the expression of anti-apoptotic genes including Bcl-2 family proteins in neuronal cells in vitro and in vivo. This study investigated detailed mechanism of GM-CSF involved in its anti-apoptotic activity and regulation of Bcl-2 expression in neural progenitor cells (NPCs) as a model. NPCs were cultured from the brain of E13 ICR mouse. When NPCs were treated with staurosporine at 1 μM, apoptosis occurred in more than 30% of cells in TUNEL assay. However, apoptosis was significantly inhibited by pre-treatment with GM-CSF at 10 ng/ml. Under the same experimental condition, the expression of both Bcl-2 and Bcl-xl was clearly induced by GM-CSF regardless of staurosporine treatment in RT-PCR and Western blot analyses. GM-CSF was shown to induce the expression of Bcl-2 and Bcl-xl via Janus tyrosine kinase (JAK) but not via phosphatidylinositol 3-kinase (PI3K) or RAS-mitogen activated protein kinase kinase-1 (MEK-1) using specific signal pathway inhibitors. Further analyses showed that the expression of Bcl-2 and Bcl-xl was induced by GM-CSF via signal transducers and activators of transcription 5 (STAT5) and STAT3, respectively. In addition, JAK/STAT5-Bcl-2 pathway but not JAK/STAT3-Bcl-xl pathway was responsible for the anti-apoptotic activity of GM-CSF in NPCs in TUNEL assay. To our knowledge, this study is the first report that shows differential roles of Bcl-2 and Bcl-xl, and their regulation mechanism involved in the anti-apoptotic activity of GM-CSF in NPCs.

Growth factors in ischemic stroke

Data from pre-clinical and clinical studies provide evidence that colony-stimulating factors (CSFs) and other growth factors (GFs) can improve stroke outcome by reducing stroke damage through their anti-apoptotic and anti-inflammatory effects, and by promoting angiogenesis and neurogenesis. This review provides a critical and up-to-date literature review on CSF use in stroke. We searched for experimental and clinical studies on haemopoietic GFs such as granulocyte CSF, erythropoietin, granulocyte-macrophage colony-stimulating factor, stem cell factor (SCF), vascular endothelial GF, stromal cell-derived factor-1α and SCF in ischemic stroke. We also considered studies on insulin-like growth factor-1 and neurotrophins. Despite promising results from animal models, the lack of data in human beings hampers efficacy assessments of GFs on stroke outcome. We provide a comprehensive and critical view of the present knowledge about GFs and stroke, and an overview of ongoing and future prospects.

Protein changes in CSF of HIV-infected patients: evidence for loss of neuroprotection

To begin to unravel the complexity of HIV-associated changes in the brain, broader, multifaceted analyses of cerebrospinal fluid (CSF) are needed that examine a wide range of proteins reflecting different functions. To provide the first broad profiles of protein changes in the CSF of HIV-infected patients, we used antibody arrays to measure 120 cytokines, chemokines, growth factors, and other proteins. CSF from HIV-infected patients with a range of cognitive deficits was compared to CSF from uninfected, cognitively normal patients to begin to identify protein changes associated with HIV infection and neurological disease progression. Uninfected patients showed relatively consistent patterns of protein expression. Highly expressed proteins in CSF included monocyte chemotactic protein-1, tissue inhibitors of metalloproteases, granulocyte colony-stimulating factor, adiponectin, soluble tumor necrosis factor receptor-1, urokinase-type plasminogen activator receptor, and insulin-like growth factor binding protein-2. Inflammatory and anti-inflammatory cytokines were expressed at low levels. HIV-infected patients showed increases in inflammatory proteins (interferon-gamma, tumor necrosis factor-alpha), anti-inflammatory proteins (IL-13), and chemokines but these correlated poorly with neurological status. The strongest correlation with increasing severity of neurological disease was a decline in growth factors, particularly, brain-derived neurotrophic factor and NT-3. These studies illustrate that HIV infection is associated with parallel changes in both inflammatory and neuroprotective proteins in the CSF. The inverse relationship between growth factors and neurological disease severity suggests that a loss of growth factor neuroprotection may contribute to the development of neural damage and may provide useful markers of disease progression.

Reduction in programmed cell death and improvement in functional outcome of transient focal cerebral ischemia after administration of granulocyte-macrophage colony-stimulating factor in rats. Laboratory investigation

OBJECT

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent hematopoietic growth factor that both enhances the survival and drives the differentiation and proliferation of myeloid lineage cells. Recent studies have suggested that GM-CSF has a neuroprotective effect against CNS injury. In this paper, the authors investigated the neuroprotective effect of GM-CSF on neuron survival and locomotor behavior in a rat model of focal cerebral ischemic injury.

MATERIALS

To understand its neuroprotective effect in vitro, GM-CSF was administered to a glutamate-induced excitotoxicity neuronal injury cell culture model that mimics the pathophysiology of focal hypoxic cerebral injury. In the animal study, the authors prepared a rat focal cerebral ischemia model by occluding the unilateral middle cerebral artery. They then examined the effects of GM-CSF administration on changes in infarct volume, apoptosis-related gene expression, and improvement in locomotor behavior.

RESULTS

Treatment with GM-CSF significantly increased cell viability in a cell culture model of glutamate-induced neuronal injury. Furthermore, in vivo administration of GM-CSF at 60 microg/kg body weight daily for 5 consecutive days beginning immediately after injury decreased infarction volume, altered the expression of several apoptosis-related genes (Bcl-2, Bax, caspase 3, and p53), and improved locomotor behavior in the focal cerebral ischemia model.

CONCLUSIONS

The GM-CSF had neuroprotective effects in in vitro and in vivo experiments and resulted in decreased infarction volume and improved locomotor behavior. Although the specific mechanism involved in stroke recovery was not fully elucidated as it was not the primary focus of this study, administration of GM-CSF appeared to decrease the extent of neuronal apoptosis by modulating the expression of several apoptosis-related genes such as Bcl-2, Bax, caspase 3, and p53. Further investigations are necessary to better understand the role of GM-CSF on neural regeneration during the recovery phase of a stroke, as well as the intracellular signal transduction pathways that mediate neuroprotection.

Cervical carotid and circle of willis arterial anatomy of macaque monkeys: a comparative anatomy study

Macaque monkeys are used in many research applications, including cerebrovascular investigations. However, detailed catalogs of the relevant vascular anatomy are scarce. We present our experience with macaque vessel patterns as determined by digital subtraction angiography of 34 different monkeys. We retrospectively analyzed digital subtraction angiograms obtained during experimental internal carotid artery (ICA) catheterization and subsequent injection of 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine. Results were catalogued according to vascular distribution and variants observed. Macaque monkeys have a bovine aortic arch. The carotid vessels generally bifurcate, but are occasionally observed to divide into three vessels. The external carotid gives rise primarily to two trunks: an occipital branch and a common vessel that subsequently gives off the lingual, facial, and superior thyroid arteries. The internal maxillary artery may be present as a terminal branch of the external carotid or as a branch of the occipital artery. The ICA is similar in course to that of the human. The anterior circle of Willis was intact in all monkeys in our study. Its primary difference from that of the human is the union of the bilateral anterior cerebral arteries as a single (azygous) median vessel. Macaque cervical carotid and circle of Willis arterial anatomy differs from humans in a couple of specific patterns. Knowledge of these differences and similarities between human and macaque anatomy is important in developing endovascular macaque models of human diseases, such as ischemic stroke.

Role of endothelial nitric oxide synthetase in arteriogenesis after stroke in mice

Arteriogenesis supports restored perfusion in the ischemic brain and improves long-term functional outcome after stroke. We investigate the role of endothelial nitric oxide synthetase (eNOS) and a nitric oxide (NO) donor, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl) amino] diazen-1-ium-1, 2-diolate (DETA-NONOate), in promoting arteriogenesis after stroke. Adult wild-type (WT, n=18) and eNOS-knockout (eNOS(-/-), n=36) mice were subjected to transient (2.5 h) right middle cerebral artery occlusion (MCAo) and were treated with or without DETA-NONOate (0.4 mg/kg) 24 h after MCAo. Functional evaluation was performed. Animals were sacrificed 3 days after MCAo for arterial cell culture studies, or 14 days for immunohistochemical analysis. Consistent with previous studies, eNOS(-/-) mice exhibited a higher mortality rate (P<0.05, n=18/group) and more severe neurological functional deficit after MCAo than WT mice (P<0.05, n=12/group). Decreased arteriogenesis, was evident in eNOS(-/-) mice compared with WT mice, as demonstrated by reduced vascular smooth muscle cell (VSMC) proliferation, arterial density and diameter in the ischemic brain. eNOS(-/-) mice treated with DETA-NONOate had a significantly decreased mortality rate and improved functional recovery, and exhibited enhanced arteriogenesis identified by increased VSMC proliferation, and upregulated arterial density and diameter compared to eNOS(-/-) mice after stroke (P<0.05, n=12/group). To elucidate the mechanisms underlying eNOS/NO mediated arteriogenesis, VSMC migration was measured in vitro. Arterial cell migration significantly decreased in the cultured common carotid artery (CCA) derived from eNOS(-/-) mice 3 days after MCAo compared to WT arterial cells. DETA-NONOate-treatment significantly attenuated eNOS(-/-)-induced decrease of arterial cell migration compared to eNOS(-/-) control artery (P<0.05; n=6/group). Using VSMC culture, DETA-NONOate significantly increased VSMC migration, while inhibition of NOS significantly decreased VSMC migration (P<0.05; n=6/group). Our data indicated that eNOS not only promotes vascular dilation but also increases VSMC proliferation and migration, and thereby enhances arteriogenesis after stroke. Therefore, increase eNOS may play an important role in regulating of arteriogenesis after stroke.

Neuroprotective properties and mechanisms of erythropoietin in in vitro and in vivo experimental models for hypoxia/ischemia

Besides its established function in erythropoiesis, erythropoietin (EPO) is currently also appreciated for its neuroprotective effects. The detrimental sequelae of prolonged cerebral hypoxia and ischemia have been shown to attenuate by EPO treatment. After binding to the EPO receptor, EPO is capable of initiating a cascade of events which--via different pathways--may lead to neuroprotection. The circumstances that determine which specific signalling route(s) are activated by EPO are largely unknown. We aim to provide the reader with a timely overview on the use of EPO in models of stroke and hypoxia-ischemia and to discuss the molecular events that underlie its neuroprotection.

A neuroprotective function for the hematopoietic protein granulocyte-macrophage colony stimulating factor (GM-CSF)

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic cytokine responsible for the proliferation, differentiation, and maturation of cells of the myeloid lineage, which was cloned more than 20 years ago. Here we uncovered a novel function of GM-CSF in the central nervous system (CNS). We identified the GM-CSF alpha-receptor as an upregulated gene in a screen for ischemia-induced genes in the cortex. This receptor is broadly expressed on neurons throughout the brain together with its ligand and induced by ischemic insults. In primary cortical neurons and human neuroblastoma cells, GM-CSF counteracts programmed cell death and induces BCL-2 and BCL-Xl expression in a dose- and time-dependent manner. Of the signaling pathways studied, GM-CSF most prominently induced the PI3K-Akt pathway, and inhibition of Akt strongly decreased antiapoptotic activity. Intravenously given GM-CSF passes the blood-brain barrier, and decreases infarct damage in two different experimental stroke models (middle cerebral artery occlusion (MCAO), and combined common carotid/distal MCA occlusion) concomitant with induction of BCL-Xl expression. Thus, GM-CSF acts as a neuroprotective protein in the CNS. This finding is remarkably reminiscent of the recently discovered functionality of two other hematopoietic factors, erythropoietin and granulocyte colony-stimulating factor in the CNS. The identification of a third hematopoietic factor acting as a neurotrophic factor in the CNS suggests a common principle in the functional evolution of these factors. Clinically, GM-CSF now broadens the repertoire of hematopoietic factors available as novel drug candidates for stroke and neurodegenerative diseases.

Colony stimulating factors (including erythropoietin, granulocyte colony stimulating factor and analogues) for stroke

BACKGROUND

Colony stimulating factors (CSFs), also called haematopoietic growth factors, regulate bone marrow production of circulating red and white cells, and platelets. They have been shown to be neuroprotective in experimental stroke. Some CSFs also mobilise the release of bone marrow stem cells into the circulation.

OBJECTIVES

To assess the effects of CSFs on functional outcome and haematology measures in patients with acute or subacute stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched November 2006), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2006), MEDLINE (1985 to June 2006), EMBASE (1985 to June 2006), and Science Citation Index (1985 to June 2006). In an attempt to identify further published, unpublished and ongoing trials we contacted manufacturers and principal investigators of trials (last contacted 2006). We also searched reference lists of relevant articles and reviews.

SELECTION CRITERIA

Unconfounded randomised controlled trials recruiting patients with acute or subacute ischaemic or haemorrhagic stroke were included. CSFs included stem cell factor (SCF), erythropoietin (EPO), granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage colony stimulating factor (GM-CSF), macrophage-colony stimulating factor (M-CSF, CSF-1), and thrombopoietin (TPO), or analogues of these. The primary outcome was functional outcome (assessed as combined death or disability and dependency using scales such as the modified Rankin Scale or Barthel Index) at the end of the trial. Secondary outcomes included safety at the end of treatment (death, impairment, deterioration, extension or recurrence), death at the end of follow up, and haematology measures (blood counts at or around day seven after treatment commenced).

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality. Study authors were contacted for additional information.

MAIN RESULTS

No large trials were identified. EPO therapy was associated with a non-significant reduction in neurological impairment in one small trial (n = 40 participants) but had no significant effect on haematological measures. G-CSF was associated with a non-significant reduction in combined death and dependency in two small trials (n = 46 participants) although there was substantial heterogeneity in this result. G-CSF significantly elevated white cell count in three trials (n = 91). Further small trials of EPO and G-CSF are ongoing.

AUTHORS' CONCLUSIONS

No large trials of EPO, G-CSF or other colony stimulating factors have been performed and it is too early to know whether CSFs improve functional outcome.

Macrophage depletion in the murine olfactory epithelium leads to increased neuronal death and decreased neurogenesis

Apoptosis of olfactory sensory neurons (OSNs) induced by olfactory bulbectomy (OBX) leads to the activation of resident macrophages within the olfactory epithelium (OE). These macrophages phagocytose degenerating OSNs and secrete chemokines, which recruit additional macrophages into the OE, and cytokines/growth factors, which regulate basal cell proliferation and differentiation and maturation of OSNs. In this study we apply for the first time the use of liposome-encapsulated clodronate to selectively deplete macrophages during the OSN degeneration/regeneration cycle in order to elucidate the role(s) of macrophages in regulating cellular mechanisms that lead to apoptosis and neurogenesis. Mice were injected intranasally and intravenously with either liposome-encapsulated clodronate or empty liposomes prior to and after OBX or sham OBX. At 48 hours after surgery the numbers of macrophages in the OE of both sham and OBX clodronate-treated mice were significantly reduced compared to liposome-treated controls (38% and 35%, respectively, P < 0.05). The reduction in macrophage numbers was accompanied by significant decreases in OE thickness (22% and 21%, P < 0.05), the number of mOSNs (1.2- and 1.9-fold, P < 0.05), and basal cell proliferation (7.6- and 3.8-fold, P < 0.005) in sham and OBX mice, respectively, compared to liposome-treated controls. In OBX mice there was also increased immunoreactivity for active caspase-3 in the OE and olfactory nerves of clodronate-treated OBX mice compared to liposome-treated controls. These results indicate that macrophages modulate the OSN population in the normal and target-ablated murine OE by influencing neuronal survival and basal cell proliferation, resulting in neurogenesis and replacement of mature OSNs.